With the kind assistance of Admin, I am currently researching the meaning of the Transneptunian planets, and have arrived at the following tentative conclusions. Please don't take them as written in stone; I expect and invite criticism.

TRANSNEPTUNIANS IN MODERN ASTROLOGY

In recent years the number of legitimate astrological bodies has increased with the discovery of several bodies beyond the orbit of Neptune. Most of these bodies are structurally similar to Pluto and are termed “planetoids” by the astronomers, who kindly tabulated them for us. I shall of course refer to them as “planets”, unless I wish to distinguish them as a class, in which case I’ll use the terms “Transneptunians” or “minor planets”. A planet is whatever we astrologers say is a planet, even if the astronomers say it's a star, satellite or planetoid. All that matters is that it moves against the background of fixed stars (etymology: asteres planetai "wandering stars" ).

1. The astrological planets have strengths (or perhaps "virtue" or "significance") following more or less the following pattern.

The luminaries SU, MO are the most powerful, each capable of ruling a sign alone.
The major planets ME, VE, MA, JU, SA, UR and NE have sufficient power to co-rule a sign. Such a planet has half the power of a luminary.

The most significant of the Transneptunians, namely Pluto, Haumea, Makemake, Eris, Snow White and Sedna seem, on first approximation, to have much less power than the major planets. I suggest that each has up to half the power of the majors, and very specific and recognizable significations.
I speak very broadly here; it is likely that SU is more "powerful" than MO, SA than ME, etc., but on the whole I feel that, as a rule of thumb, a minor planet is worth half a major planet, and major planet is worth less than half a luminary.

2. I suggest the rulership scheme in the attached document "Schema".

For example, suppose a native has LE rising. Then the Chart ruler is SU, and we can look to the condition of this to gain considerable insight as to the native's life. A native with, say, SG rising is more problematic, and we must look to the condition of both JU and NE to learn as much as we would, in the first chart, from the SU alone.

Now consider TA rising. We have hitherto looked only to VE as chart ruler, and of course gained much insight in doing so. But we now have VE, ER and MK to consider. This does not diminish the contribution of VE, but adds information specific to the natures of ER and MK. Together, they should be given as much importance as VE, but alone, each will contribute half or less than half the information we get from VE.

Haumea, Eris and Sedna have been thoroughly investigated and I advance suggested aspect meanings in the relevant threads. Work on Makemake is currently under way. The attribution of SW is largely due to the name- ephemerides are not yet (03/09/2013) extant. More Transneptunians (probably) remain to be discovered, and I shall place these where appropriate. A case may be made for certain minor bodies within the orbit of Neptune, notably Chiron; this may be placed in Sagittarius and Pisces. I suggest that the Transneptunians (Pluto included) be used only with the major aspects and sextiles.

PLEASE NOTE

The material given here, although thoroughly investigated from the perspective of a single researcher, cannot be the whole story. Any Forum Member who consults the material is warned to trust their own intuitions before mine. I hope that Forum Members will post their experiences and opinions of the material in the relevant forums, especially if critical. This will enable the process of addenda and revision necessary to a more complete view of these planets.

Members of the Forum may consult this material freely, and may use this material in horoscope interpretation without acknowledgement. However, if the material is employed in any work of analysis or criticism, please credit to "Mersenne the Astrologer" (2013) Transneptunian Planets. Available at the Astrologers' Forum, [please add a link and give the last date of access]

The aspects given are the result of analysing some hundred or so celebrity/historical charts. Hopefully, as they stand, they will seem reasonable. The acid test, however, comes in the integration of the aspect keywords with the whole chart.

The Transneptunians (Pluto included) are not as powerful as the traditional planets. Elsewhere I suggest, as a rule of thumb, that SU and MO are twice as powerful as ME VE MA JU SA NE UR, and that these are more than twice as powerful as the Transneptunians (I'll use TN as an abbreviation). So no TN could add more than about 3% of information to the chart (roughly and optimistically).

The best we can hope for, then, is that a particular TN, in close major aspect (0, 60, 90, 120, 180 degrees) to a major planet SU MO ME VE MA JU SA UR NE, will do one of the following.

a) Add a piece of information that confirms the trend of the major planet. For example, Mars in Pisces square Mercury in Gemini indicates a certain nerviness (not the same as nervousness; think alertness with an aggressive edge), which will typically attach to any decision the native makes. In particular, the native will always think of something better they could have done. Sedna in close aspect to either of these bodies will confirm this, adding the ability to construct scenarios confirming the native's suspicions.

b) Or, it will add a contrary piece of information that would otherwise be surprising- a kink. Returning to the Mars square Mercury example. Haumea in very close aspect to either body will tend to diminish the regret and self-analysis of the square, making for a native who rarely revisits or regrets his decisions, unless there is evidence to indicate he should do so.

We don't have much information about the TNs' behaviour in different signs, but going by PL, the traditional Sign keywords will work fine. So any TN will be in an intellectual mood in Air, emotional in Water, practical in Earth and inspirational in Fire.

I hope that those Forum members who practice astrology will make trial of the aspect keywords I offer. This is best done in one's own chart. Do the TNs confirm, or explain a kink that has otherwise puzzled you? If you're composing someone else's chart, why not do the chart as you've always done, then consider how the TNs might change some small part of it? You could submit the conventional chart, and just ask for an opinion regarding the extra information.

I've now posted aspect keywords for Makemake (in its own thread), but I am concerned as to the lack of feedback. I believe my technique is correct, but I have my own psyche with its particular biases and blindnesses, and your opinions are needed to round out the picture. I request that anyone who accesses the keywords from now on share their own impression of the Transneptunians' impact in their own charts.

Since all of the other planets are placed in the zodiac based on the distance of their orbits it would only make sense to do the same for the plutoids. Perhaps having it based on the resonances of Neptune would be a good starting point. Here's an idea:

Has anyone noticed how similar the orbits of the eight major planets are compared to 'big four' asteroids and plutoids? Mercury is to Jupiter what Vesta is Pluto, etc. Enlarge a map of the orbits of the four inner terrestial planets and the 'big four' asteroids by sixteen times and it looks eerily the same as that of the four outer jovian planets and the 'big four' plutoids.

The spirit of Bode lives! I've been playing around with the datasets I've posted, and wondering if there might be an harmonic relationship between "old" and "new" Planets with similar occupation spectra. Yours might be a more direct way of establishing such a relationship, or at least of supporting it.

Please excuse the late reply, but as you know, the day job can be a tad demanding.